1. Field of the Invention
The present invention relates to a revolving apparatus for a work vehicle.
2. Background Information
An upper revolving unit having a work implement or the like, and a lower traveling unit having crawlers are provided to a work vehicle such as a hydraulic excavator. In the case of a hydraulic excavator, for example, the work implement is constituted by a boom, an arm, a bucket, or the like.
A revolving apparatus comprising a swing motor, swing machinery, and an output pinion is provided in order to make the upper revolving unit revolve with respect to the lower traveling unit. Meanwhile, a swing circle is provided to the lower traveling unit. The swing machinery is equipped with a brake unit, a deceleration unit for decelerating the rotational drive force from the swing motor, or the like and the output pinion disposed on the lower side of the swing machinery meshes with teeth provided on the inside or outside of the swing circle. The rotational drive force of the swing motor is transmitted to the output pinion, and the swing machinery rotates on the inside or outside of the swing circle, the result being that the upper revolving unit revolves with respect to the lower traveling unit.
Here, a brake unit that halts the revolution is provided in the interior of the swing machinery. A brake unit such as this is disclosed in Japanese Laid-Open Patent Application 2008-232270, for example. FIG. 11 shows the internal structure around the brake unit of the swing machinery disclosed in Japanese Laid-Open Patent Application 2008-232270. In Japanese Laid-Open Patent Application 2008-232270, a mechanical brake 1000 is provided as a brake unit. This mechanical brake 1000 brakes the rotation of a drive shaft 1001. The mechanical brake 1000 is configured so that a brake disk 1002 joined to the drive shaft 1001 can be squeezed and held by a brake piston 1004 whose up and down motion is controlled via brake pads 1003, and this squeezing can be released.
A spring member 1005 provided to the upper part of a brake piston 1004 imparts a downward biasing force to the brake piston 1004. This spring member 1005 is disposed in a concave component 1006a formed in a housing 1006 provided to the upper part of the brake piston 1004. The downward biasing force provided by the spring member 1005 causes the brake piston 1004 to squeeze and hold a brake disk 1002, resulting in a state in which the brake is actuated. Also, the up and down sliding of the brake piston 1004 is controlled by supplying and discharging hydraulic fluid to and from a hydraulic chamber 1007. When hydraulic fluid is supplied to the hydraulic chamber 1007, the brake piston 1004 compresses the spring member 1005 while being pushed upward. This releases the clamped state of the brake disk 1002 by the brake piston 1004, and releases the braking.